Pretoria , South Africa -LRB- CNN -RRB- -- Oscar Pistorius is a heartbroken man who has to live with the fact that he killed the love of his life , his uncle has told CNN in an exclusive interview .

For the past three months , the double amputee sprinter has been living at his Uncle Arnold 's house in Pretoria . He has grown a beard because he does n't want to be recognized , and has surrounded himself with photos of Reeva Steenkamp , his uncle says .

Pistorius is charged with murdering the 29-year-old model and law school graduate early on February 14 , and faces a court hearing next Tuesday .

Arnold Pistorius described the runner 's grief as `` unthinkable '' and says his heart bleeds for his nephew . `` He 's got photos in his room , photos all over the place . He 's housebound , you know . He does n't go out in public places .

Bloody photos of scene of killing leaked

`` What can you say if the person you love the most dies , and you were the instrument ? How would you feel ? It 's unthinkable . ''

Pistorius says Steenkamp 's death was an accident and that he mistook her for a burglar . The state says it was murder . A trial date has not been set .

The sprinter 's agent has also spoken for the first time about the 4 a.m. call he received telling him there had been a shooting at the track star 's home .

`` It was the estate where Oscar -LRB- was -RRB- staying at , the estate manager 's daughter phoned me from Oscar 's phone . So I picked up the phone and saw it was Oscar 's number and thought it was him phoning me . And just had this voice of a girl frantically on the other side shouting , ` Please , you have to rush over here , you have to come to Oscar 's house , ' '' Peet van Zyl told CNN in an exclusive interview .

`` I initially thought it was Oscar that has been shot . She said , ` No , no , no , no . Reeva 's been shot . ' She explained then to me basically just briefly what happened . And yeah , total shock obviously . So I had to jump in the car and rush through to Pretoria . ''

Van Zyl said he then called Ampie Louw , the sprinter 's coach , and told him to jump in his car and get to Pistorius 's house .

`` When arrived at the house and you see all the police cars and lights ... I was standing outside , me and Peet and the lawyer , but Oscar was inside , '' Louw told CNN .

`` I could hear him crying in the garage , and Reeva was at the entrance . So that was terrible for me . ''

Pistorius will make a brief appearance Tuesday at the Pretoria Magistrates Court , which will hear a motion by state prosecutors to postpone the case for further investigations . The trial itself may not happen until early 2014 .

READ MORE : Not everyone surprised at Oscar Pistorius ' fall from grace

READ MORE : Pistorius , and the psychology of walls

CNN 's Nick Thompson contributed to this report .

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Exclusive : Uncle says Pistorius 's grief over killing of Reeva Steenkamp ` unthinkable '

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Pistorius has grown a beard and is surrounded by photos of Steenkamp

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CNN 's Robyn Curnow first reporter to speak to ` Blade Runner ' at uncle 's Pretoria home

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Pistorius charged with murdering Steenkamp on February 14 ; has court hearing Tuesday